Hot-gas reciprocating apparatus with power control device

ABSTRACT

A hot-gas reciprocating apparatus with a power control device for controlling the amount by weight of working fluid in the working space.

[45] Jian. 14, 1975 United States Patent t191 Reininlk [54] HOT-GAS RECIPROCATTNG APPARATUS References Cited UNITED STATES PATENTS WITH POWER CONTROL DEVICE [75] Inventor:

[Frits Reinink, Emmasingel, Eindhoven, Netherlands [73] Assignee: U.S. Philips Corporation, New

York, N.Y.

22 Filed! A ll. 29 1974 l 1 p Primary Examiner-Martin P. Schwadron [21] Assistant Examiner-Allen M. Ostrager Attorney, Agent, or Frm-Frank R. Trifari Appl. No.; 465,312

[30] Foreign Application Priority Data ABSTRACT A hot-gas reciprocating apparatus with a power con- May l5, 1973 Netherlands......................... 736711 HOT-GAS RECIPROCATING APPARATUS WITH POWER CONTROL DEVICE BACKGROUND OF THE INVENTION The invention relates to a hot-gas reciprocating apparatus comprising at least one cylinder in which at least one piston-shaped body connected by a piston rod to a driving means is reciprocable. One end face of this body influences the volume of a working space, while between the cooperating walls of the piston and the cylinder at least two axially spaced sealing elements are provided which are accommodated in grooves in the wall of the piston or cylinder and bound an intermediate space which separates the working space from a further space. A device is provided for controlling the amount by weight of the working fluid in the working space, which device has a storage container for working fluid which can communicate with the working space via a duct formed in the piston rod. A hot-gas reciprocating apparatus of the type referred to is described in U.S. Pat. No. 2,611,237.

The term hot-gas reciprocating apparatus is used herein to denote hot-gas reciprocating engines, coldgas refrigerators and heat pumps. In the working space of such apparatus the working fluid is alternately compressed when it is contained mainly in a part of the working space, i.e., the compression space, then transferred via a regenerator to another part, the expansion space, subsequently expanded while being contained mainly in the expansion space, and finally returned via the regenerator to the compression space, thus completing the cycle. The compression and expansion spaces have different mean temperatures in operation.

By means of the device for controlling the amount by weight of working fluid in the working space of the hotgas reciprocating apparatus, the power of this apparatus can be varied by variation of the mean level of the pressure of the working fluid in the working space.

In the apparatus described in U.S. Pat. No. 2,61 1,237 the storage container is periodically caused to communicate with the working space, in that a port formed in the piston rod guide and communicating with the storage is periodically uncovered by a duct in the connecting rod during its reciprocating movement. The sealing elements between the cooperating walls of the piston and the cylinder seal the working space from the further space, which may be the crankcase or, for example in double-acting apparatus, a second working space. Owing to the internal ductsystem the known apparatus has the advantage of compact construction.

In systems for continuous power control of hot-gas reciprocating apparatus by means of control of the mean level of the pressure of the working fluid in the working space, two separate ducts connecting the storage container and the working space are generally used at present (U.S. Pat. Nos. 3,372,539 and 3,546,877). The first duct, which contains a non-return valve opening towards the working space, serves to supply working fluid to this space. The second duct, which contains a non-return valve which inhibits flow of working fluid to the working space, is used to discharge working fluid from the working space. In the apparatus according to the present invention one of these two ducts is constituted by the communication between the storage container and the working space via the duct formed in the piston rod.

Multi-cylinder hot-gas reciprocating apparatus require two non-return valves for each working space which are located in the associated ducts as near as possible to the working space in order to reduce the size of the dead space formed by the duct parts between the working space and the said valves to a minimum. In the case of multi-space apparatus this means the use of a large number of non-return valves.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hot-gas reciprocating apparatus of the type referred, to in which the provision of the sealing elements between the piston and the cylinder is profitably used to reduce the total number of ancillary components required in the apparatus to a minimum, while retaining the sealing of the working space from the further space, and to reduce the dead space of the working space.

A hot-gas reciprocating apparatus according to the invention is characterized in that the duct formed in the piston rod extends at the end remote from the storage container in the piston-shaped body and opens in the intermediate space; element which separates the intermediate space from the working space together with the associated groove is constructed as a non-return valve which permits working-fluid flow in one direction only.

This combination of steps ensures that the sealing element between the intermediate space and the working space also performs the function of a non-return valve for the power control system. Hence separate nonreturn valves for the respective ducts may be dispensed with. Because the sealing element according as a nonreturn valve immediately adjoins the work-ing space, substantially no dead space is produced.

It should be noted that it is known from the aforementioned U.S. Pat. Nos. 3,372,539 and 3,546,887 to design a sealing ring (piston ring) as a non-return valve. The said patents refer to apparatus having a buffer space at the side of the piston remote from the working space, working fluid being permitted to flow from the working space past the piston ring to the buffer space. There is no question of supplying working fluid to or discharging working fluid from the working space via a duct in the piston and the piston rod or in the displacer and the displacer rod whilst the working space is required to remain sealed from the further space situated at the side of the piston remote from the working space, as is the case in the apparatus according to the invention.

An advantageous embodiment of a hot-gas reciprocating apparatus according to the invention is the form of a double-acting hot-gas reciprocating engine in which the piston by one of its end faces influences the volume of an expansion space which forms part of a first working space and in operation has a higher mean temperature; the other end face ofthe piston influences the volume of a compression space which forms part of a second working space and in operation has a lower mean temperature. The invention is characterized in that only the sealing element which separates the intermediate space from the compression space of the second working space together with the associated groove is constructed as a non-return valve.

This provides the advantage that in the case of power control it is always ensured that working fluid at a lower temperature enters or leaves the lowertemperature part of the working space. Thus hot working fluid does not find its way into the discharge part, and cold working fluid does not reach that side of the regenerator included between the expansion space and the compression space which is at a higher temperature and faces the expansion space. The latter would give rise to imbalance in the regenerator, which would reduce the thermal efficiency of the engine.

In an advantageous embodiment of a hot-gas reciprocating apparatus according to the invention in the form of a double-acting hot-gas reciprocating engine, the non-return valve opens towards the compression space. As a result, in normal operation in the duct within the piston and the piston rod, a pressure is obtained which is substantially equal to the minimum pressure produced in the variable-pressure working space. Consequently the gas pressure above the seals between the piston rod and the surrounding guide which communicate with the duct, is low also. The pressure on the other side of the seals may then be proportionally lower. For rolling diaphragm seals supported by a liquid (U.S. Pat. No. 3,241,379) this means that the pumping device for supplying supporting liquid is required to produce a lower liquid pressure.

BRIEF DESCRIPTION OF THE DRAWING An embodiment of the invention will now be described by way of example with reference to the accompanying diagrammatic drawing; the single FIGURE is a longitudinal sectional view of a four-cylinder double-acting hot-gas reciprocating engine shown not to scale.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the FIGURE, reference numerals l, 2, 3 and 4 denote cylinders in which pistons 5, 6, 7 and 8 respectively can reciprocate. The pistons are connected by piston rods 9 to 12 and connecting rods 13 to 16 respectively to a crankshaft 17; the cranks 18 to 2l are at such angles (of 90) to one another that the desired phase differences of the movements of the pistons are obtained. The crankshaft 17 is led out through the wall of a crankcase 22.

The pistons to 8 vary the volumes of expansion spaces 23, 24, and 26 respectively by their upper end faces and the volumes of compression spaces 27, 28, 29 and 30 respectively by their lower end faces. The expansion space 23 in the cylinder 1 and the compression space 28 in the cylinder 2 with which it communicates by a duct 31 together form a working space in which a thermodynamic cycle takes place. Further working spaces are constituted by the expansion space 24 and the compression space 29 which communicate via a duct 32, by the expansion space 25 and the compression space which communicate via a duct 33, and by the expansion space 26 in the cylinder 4 and the compression space 27 in the cylinder 1 which communicate via a duct 34.

Heat is supplied from the exterior to the working fluid in the four cycles in the expansion spaces 23 to 26 by means of burners a to 35d respectively. Each of the connecting ducts 3l to 34 includes a regenerator 36, 37, 38, 39 respectively and a cooler 40, 4l, 42 43 respectively.

In each cylinder the expansion space of one cycle is sealingly separated from the compression space of another cycle by means of two piston rings accommodated in spaced grooves in the piston wall. The piston rings are denoted by reference numerals 44 to 5l. Each pair of piston springs bounds an intermediate space 52, 53, 54,55 respectively. The lower piston rings 48 to 5l, which are accommodated with a certain amount of clearance in associated grooves 56 to 59 respectively, having radial grooves 48a to 51a respectively formed in their lower surfaces. Thus there always is open communication between the adjacent compression space and the space between the facing vertical surfaces of the piston ring and the piston groove. The open communication may alternatively be established by forming the radial grooves in the lower surfaces of the piston grooves 56 to 59.

A storage container 60 for working fluid communicates via a duct 6l formed in the wall of the crankcase 22 with annular ducts 62 to 65 which during the reciprocating motion of the piston rods 9 to l2 continuously are in open communication with ducts 66 to 69 respectively in these rods. The latter ducts extend in the respective pistons 5 to 8 and open in the associated intermediate spaces 52 to 55. A valve 70 is interposed between the storage container 60 and the duct 6l.

In normal operation the valve 70 is closed and the pressure in the ducts 66 to 69 and the intermediate spaces 52 to 55 is at least substantially equal to the minimum pressures prevailing in the working spaces. The higher mean pressure in, for example, the compression space 27 ensures that the piston ring 48 with its upper surface remains in engagement with the upper wall of the groove 56, so that the space 27 remains sealed from the intermediate space 52. The piston ring 44 seals the expansion space 23 from the intermediate space 52. Because the level of the pressure in the expansion space 23 is higher than that in the intermediate space 52, the piston ring 44 is additionally urged into engagement with the lower surface of the piston groove accommodating it.

When the power of the engine is to be increased by supplying high-pressure working fluid from the storage container 60, the valve 70 is opened. When the pressure in the duct 66 and the intermediate space 52 exceeds the variable cycle pressure in the compression space 27, the lower surface of the piston spring 48, in which surface the radial grooves 48a are formed, is thrust into engagement with the lower surface of the groove S6. Working fluid then flows from the storage container 60 via ducts 61 and 66, intermediate space 52 and radial grooves 48a to compression space 27. When the power is to be reduced, working fluid is withdrawn from the working spaces via a discharge pipe, not shown.

By means of the construction described, comparatively cold working fluid is supplied to the colder part of the cycle. If cold working fluid could be supplied to the expansion spaces 23 to 26 via the piston rings 44 to 47 respectively (which in this case would be constructed as non-return valves), the balance of the regenerators 36 to 39 would be upset and the thermal efficiency of the engine would be reduced.

Since normally the minimum working fluid pressure prevails in the annular ducts 62 to 65, the pressure in the crankcase 22 also may be comparatively low. lf liquid-supported rolling diaphragms are provided as seals for separating the annular ducts 62 to 65 from the crankcase, the pressure of the liquid at the sides of these rolling diaphragms remote from the annular ducts may be low. This is of advantage for the pump which supplies liquid to the space beneath each rolling diaphragm and which may be a pumping ring.

What is claimed is:

1. A hot-gas reciprocating apparatus provided with at least one cylinder in which a piston connected via a piston rod to a driving means is reciprocable, at least one end face of this piston influencing the volume of a working or compression space, while between the c0- operating walls of the piston and the cylinder at least two axially spaced sealing elements are provided which are accommodated in grooves formed in the said piston wall or cylinder wall and bound between them an intermediate space which separates the working space from an expansion space, the apparatus having in combination therewith the improvement of a device for controlling the amount by weight of working fluid in the working space, which device comprises a storage container for working fluid which can be caused to communicate with the working space via a duct, the duct formed in the piston rod extends with its end remote from the storage container opening into the intermediate space, and the sealing element which separates the intermediate space from the working space together with the associated groove is constructed as a non-return valve which allows workingfluid flow in one direction only from the intermediate space to the working space.

2. Apparatus according to claim 1 and constructed as a double-acting hot-gas reciprocating engine, in which the piston with one end face influences the volume of an expansion space which forms part of a first working space and in operation is at a higher mean temperature, and its other end face influences the volume of a compression space which forms part of a second working space and in operation is at a lower mean temperature, wherein only that sealing element which separates the intermediate space from the compression space of the second working space together with the associated groove is constructed as a non-return valve.

3. Apparatus according to claimi 2 wherein the nonreturn valve opens towards the compression space.

i= k s i :k

gygj) e UNHTED STATES PATENT @met CERTW'CTE @@CTN Patent No. 3,859,792 Dated January 14, 1975 Inventor@ Fai-.'11s REININK It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

- In the Title: a

Cancel Priority No. "7367711" and insert "7306711" Col. l, line 2, cancel "at least one piston-shaped body" and insert --a piston-- Signed and sealed this 11th day of March 1975.

(SEAL) Attest: l

RUTH c MASON C MARSHALL DANN Attesting Officer Commissioner of Patents and Trademarks 

1. A hot-gas reciprocating apparatus provided with at least one cylinder in which a piston connected via a piston rod to a driving means is reciprocable, at least one end face of this piston influencing the volume of a working or compression space, while between the cooperating walls of the piston and the cylinder at least two axially spaced sealing elements are provided which are accommodated in grooves formed in the said piston wall or cylinder wall and bound between them an intermediate space which separates the working space from an expansion space, the apparatus having in combination therewith the improvement of a device for controlling the amount by weight of working fluid in the working space, which device comprises a storage container for working fluid which can be caused to communicate with the working space via a duct, the duct formed in the piston rod extends with its end remote from the storage container opening into the intermediate space, and the sealing element which separates the intermediate space from the working space together with the associated groove is constructed as a non-return valve which allows workingfluid flow in one direction only from the intermediate space to the working space.
 2. Apparatus according to claim 1 and constructed as a double-acting hot-gas reciprocating engine, in which the piston with one end face influences the volume of an expansion space which forms part of a first working space and in operation is at a higher mean temperature, and its other end face influences the volume of a compression space which forms part of a second working space and in operation is at A lower mean temperature, wherein only that sealing element which separates the intermediate space from the compression space of the second working space together with the associated groove is constructed as a non-return valve.
 3. Apparatus according to claim 2 wherein the non-return valve opens towards the compression space. 